This disclosure relates generally to polymeric foams with nanocellular morphology and methods of making the polymeric foams. More particularly, the disclosure relates to polymeric foams that include a polymer and/or copolymer having structural units derived from 2-phenyl-3,3-bis(hydroxyphenyl)phthalimidine compounds.
Polymer foams have been prepared by diffusing a polymer blowing agent and/or foaming agent into the desired polymer. Solubility of the polymer-blowing agent in the host polymer is a factor that can determine the cell size. Solubility is generally limited such that microcellular morphology is the smallest cell size attainable with various blowing agents and polymer systems. In the past, solubility was increased by use of a high-pressure gas injection system, which is relatively expensive due to the high-pressure requirements. Other methods to increase solubility included the addition of additives, which can increase the polymer solubility for the polymer blowing agent but has also been found to depress the glass transition properties of the host polymer.
There remains a need in the art for improved methods for increasing solubility of the polymer blowing agent in the polymer. It would be desirable to have a composition that provides for increased blowing agent solubility without the need for additives and that does not depress the glass transition temperature. The solubility of the polymer blowing agent in the host polymer system should be effective to provide nanocellular morphology.